Voltage regulator system for secondary batteries

ABSTRACT

To permit charging of secondary batteries by electrical power at a voltage which is just below the gassing voltage of the battery, a temperature sensing device is placed on the holder for the battery, spring-pressed against the battery so that the actual battery temperature will be sensed. The sensed temperature then is utilized to control the voltage regulator to vary the charge voltage in accordance with actual battery temperature to provide for most rapid and safe charging under all battery operating conditions.

United States Patent 1 Jache Oct. 2, 1973 [54] VOLTAGE REGULATOR SYSTEMFOR 3,274,477 9/1966 Boyes 320/35 SECONDARY BATTERIES 2,498,814 2/1950Little et al. 320/35 3,609,505 9/1971 Harland et al. 320/35 [75]Inventor: Otto Jache, Budingen, Germany [73] Assignee: Accumulatorenfabrik Sonnenschein Primary Examiner j Miner Budmgen Germany AssistantExaminerRobert J. Hickey 22 Filed; May 24 1972 Attorney-Flynn & Frishauf[21] Appl. No.: 256,521

[57] ABSTRACT [30] Foreign Application Priority Data T t h f d b u b I tI operml c argingo secon ary a eries yeec rica June 8, 1971 Germany P 2128 51009 power ata voltage which is j below the g g volt age of thebattery, a temperature sensing device is [52] 11.5. CI 320/35, 320/2,placed on the holder for the battery, springpressed 1 Int K "01 45/0'4against the battery so that the actual battery tempera- J'J Z 36 turewill be sensed. The sensed temperature then is uti- [56] ReferencesCited UNITED STATES PATENTS 2,206,306 7/1940 Sager 136/171 X lized tocontrol the voltage regulator to vary the charge voltage in accordancewith actual battery temperature to provide for most rapid and safecharging under all battery operating conditions.

8 Claims, 3 Drawing Figures VOLTAGE REGULATOR SYSTEM FOR SECONDARYBATTERIES The present invention relates to a voltage regulator system inthe charging circuits of secondary batteries, and more particularly tovoltage regulator systems for secondary batteries used in automotivevehicles and the like. In such systems, voltage regulators control thevoltage being applied to the battery to charge the battery as thevehicle engine operates. The charge voltage should be limited to apredetermined maximum value. This maximum value is highly temperaturedependent.

Charging arrangement, particularly for automotive vehicles, have voltageregulators in which the electrical supply or charging voltage is heldbelow a predetermined voltage of the secondary battery, in order toinsure long battery life. Voltage regulators have been proposed in whichtemperature sensing elements are provided to adjust the supply voltagein dependence on temperature of the electrolyte of the battery. Suchknown regulators'utilize a thermistor inserted into a cell of thebattery so as to be sensitive to the temperature of the electrolytewithin the battery cell. To install a temperature sensing element withina battery, the latter, however, must be provided with a specificmounting means. When a battery is replaced by a new one, thetemperaturesensor must be detached and installed in the new one.

Batteries should give as little trouble in installation and operation aspossible. Lead-acid type batteries should be charged preferably in sucha manner that the electrical power for re-charging is applied atvoltages which are just below the gassing voltage, so that wheneverpower has been taken from the battery is reapplied to the battery in asshort a period of time as possible, without decomposition of theelectrolyte, and thus loss of water by electrolytic decomposition. Thegassing voltage of lead-type batteries exhibits a substantial negativetemperature coefficient, that is, the gassing voltage drops as thetemperature increases.

It is an object of the present invention to provide an improved voltageregulator system wherein a battery will be charged fully and safelywithout insertion of a temperature sensor into the battery.

SUBJECT MATTER OF THE PRESENT INVENITON Briefly, a temperature sensingelement is located to automatically contact a battery in good heattransfer relation when the battery is inserted into the holder.

The temperature sensing element is permanently and fixedly connected tothe voltage regulator which control battery charge voltage to a levelwhich depends on actual, sensed battery temperature. This charge voltagelevel is preferably set to be just below the gassing voltage.

In accordance with a preferred embodiment, the temperature sensor islocated at the side, or below'the holding plate or holding assembly forthe battery, and spring-pressed against the battery. The sensor can becombined with a voltage regulator, particularly with an solid stateelectronic voltage regulator. Thus, when the battery itself is changedor moved, no structural changes or changes of interconnections to thetemperature sensing elements themselves have to be made. The outputsignal of the temperature sensor which is directly representative ofactual battery temperature then is utilized as a control value todetermine the maximum value of the charge voltage so that the chargevoltage, at any temperature, is just below the gassing voltage of thebattery itself.

Voltage regulators of a type particularly useful in connection with thepresent invention are shown in US. Pat. No. 3,296,516. In order tointroduce a correcting signal from a temperature sensing element intothe circuit, a thermistor is connected in circuit with a voltage dividerto modify the charge voltage setting of the voltage divider in responseto battery temperature such that the rate of change of charge voltagesetting of the regulator due to temperature increase will be about thesame as the rate of change in gassing voltage of the battery due to suchtemperature increase.

The invention will be described by way of example with reference to theaccompanying drawings, wherein:

FIG. 1 is a vertical cross-sectional view through a holder for abattery, in which a sensing element coupled to a voltage regulator islocated in the bottom, the battery being shown schematically;

FIG. 2 is a vertical cross-sectional view through a similar arrangementin which the temperature sensing element is located at the side of thebattery; and

FIG. 3 is a graphical illustration of the maximum charge voltagecontrolled in accordance with the invention and of the gassing voltageversus temperature of a battery.

A base plate 1 has a battery, schematically shown at 2 placed thereon.Base plate 1 is secured in a usual and customary manner, as desired, ina motor vehicle. It is, preferably, formed with laterial guide strips orplates 3 to hold the battery in place. To secure the battery to the baseplate, clamps 4, 5 are provided, to be clamped by screws (not shown)against the bottom plate and engaging small notches formed in thebattery, that is, to fit over transverse ridges 6, 7, remaining belowthe notches of the battery. Various other ways to hold the battery inplace can be used, for example hold-down straps passing across thebattery from the top, or the like, as desired.

The base plate I of the battery holder has an opening 8 formed centrallytherein, in which a voltage regulator 9 is located,-to control thecharge voltage to the battery. Regulator 9 is preferably of theelectronic type, as shown in U.S. Pat. No. 3,296,516, and utilizes aprinted circuit. A temperature sensing element 10 is provided, whichmeasures the actual temperature of the battery. Sensor 10 is placed onthe surface of the voltage regulator which faces the battery. Thevoltage regulator 9 is held within the opening 8 by means of springs 11,which press the regulator 9 and the temperature sensor 10 securedthereto in the direction of the bottom wall of the battery, to provide agood contact between the temperature sensitive element 10 and thebattery itself. The temperature sensitive element 10, preferably, is athermistor.

As shown in FIG. 3, the output signal of the temperature sensor isutilized as a control signal to control the voltage to charge thebattery to a value which is just below the gassing voltage of thebattery. In a preferred form, the temperature sensor is insulatedagainst outside temperature disturbances. As shown in FIG. I, theregulator 9 is covered with a temperature insulating layer 9' throughoutits circumference, except on the surface facing the battery itself. Itis also possible to insulate the entire opening 8, see FIG. 2, where theopening in the base plate is arranged in form of a cavity which iscompletely lined on the inside wih temperature insulation material 9".Thus, the temperature sensor itself is insulated against interferingoutside temperature disturbances. Controller 9 is connected over a cable12 to the usual alternator or other charging element, to be driven by aprime mover.

If the battery 2 is to be replaced, or removed from the holder, noconnecting lines need be broken, since there is no actual electrical orfixed mechanical connection between the voltage regulator and thetemperature sensor on the one hand, and the battery on the other; thevoltage regulator is merely held in place by spring 11, which now willproject the entire unit slightly above the base plate 1.

The embodiment of FIG. 2 illustrates a cavity 8' in which the voltageregulator 9 is located. Cavity 8' is located in the side wall 13 of thebattery holder, so that the temperature sensor 10 of the voltageregulator is pressed against the side wall of the battery to havethermal conductive contact therewith.

In the embodiment shown, the temperature sensor is formed as one unitaryelement with the voltage regulator. It is equally possible to locate thevoltage regulator at any desired place within the motor vehicle, forexample where convenient for servicing, or at or in combination with themotor vehicle alternator, and to place only a temperature sensingelement in such a position that the temperature of the battery itselfwill be sensed, by contact with the bottom or side wall of the battery.Again, the temperature sensing element itself should be pressed againstthe battery by springs or the like, in order to provide for good heattransfer between the battery and the temperature sensor and to avoid thenecessity of connecting or re-connecting additional electrical terminalsif the battery is to be moved or changed. In a preferred form, however,the temperature sensor and the voltage regulator are combined as asingle unit, the entire unit being made as a replaceable element in caseof malfunction of any of the components thereof.

Various changes and modifications may be made within the inventiveconcept.

I claim:

1. In a voltage regulator system for secondary batteries 2 in which thebattery 2 is charged from a source of variable voltage;

a holder means 1, 3, 4, 5, 13 holding the battery in a fixed locationincluding a member 1, 13 located adjacent the battery when the batteryis placed against the holder means;

a voltage regulator 9 limiting the charge voltage to a predeterminedvalue;

and temperature sensitive means providing an electrical signal connectedto the voltage regulator to affect charge voltage in dependence onbattery temperature;

the improvement wherein said member 1, 13 of the holder means adjacentthe battery 2 is formed with a cavity therein, the temperature sensingmeans 10 being an element mechanically separate from the battery 2 andlocated in the cavity to contact the outside wall of the battery and tobe in heat transfer relation therewith to sense battery temperature.

2. System according to claim 1, wherein resilient means 11 are providentresiliently biassing the temperature sensor into contact with thebattery wall.

3. System according to claim 2, wherein the temperature sensor islocated against the bottom wall of the battery.

4. System according to claim 2, wherein the temperature sensor islocated against the side wall of the battery.

5. System according to claim 2, wherein the voltage regulator and thetemperature sensor form one integral unit, said unit beingspring-pressed by said resilient means against the battery.

6. System according to claim 1, wherein the temperature sensor andvoltage regulator form an integral unit located in the cavity andresiliently held therein with the temperature sensor facing the batterywhen the battery is located in position with respect to the holdermeans.

7. System according to claim 6, wherein the member is plate-like andformed with a closed cavity, the temperature sensor-voltage regulatorunit and the resilient means being located in said cavity;

and thermal insulation means are located at least in part in said cavityto insulate the temperature sensor from outside temperaturedisturbances.

8. System according to claim 1, further comprising thermal insulatingmeans insulating the temperature sensor against outside temperaturedisturbances and surrounding the temperature sensor at least in part.

UNITED STATES PATENT OFFICE CERTIFICATE OF CRRECTIUN Patent No. 3 763,416 Dated October 2 1973 Inventor (s) Otto Jache It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the claims:

All reference numerals:

should have parentheses placed there around, since these are referencenumerals,

Signed and sealed this 12th day of February 1974.

(SEAL) Attest:

EDWARD.M.FLETHER,JR. C0 MARSHALL DANN Attestlilg Offlcer Comissioner ofPatents F powso 0-69) usco M-Dc 60376-P69 E U.S. GOVERNMENT PRINTINGOFFICE I969 0-356-33fl.

UNITED STATES PATENT OFFICE CERTIFICATE OF CURRECTIUN Patent No. 3 763,416 Dat d October 2 1973 Inventor(s) Otto Jache It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the claims:

All reference. numerals; 2,2, l, 3, 4, 5, l3, 1, l3, 9, 1, l3, 2, l0, 2,ll

should have parentheses placed there around, since these are referencenumerals,

Signed and sealed this 12th day of February 197 (SEAL) Attest:

EDWARD M.FLET( IHER,JR. co MARSHALL DANN Attestlng offlcer- Commissionerof Patents FORM po'wso P- uscoMM-Dc scan-pe ff U.S. GOVERNMENT PRIN'FHGOF FICE I969 0-366-334,

1. In a voltage regulator system for secondary batteries 2 in which thebattery 2 is charged from a source of variable voltage; a holder means1, 3, 4, 5, 13 holding the battery in a fixed location including amember 1, 13 located adjacent the battery when the battery is placedagainst the holder means; a voltage regulator 9 limiting the chargevoltage to a predetermined value; and temperature sensitive meansproviding an electrical signal connected to the voltage regulator toaffect charge voltage in dependence on battery temperature; theimprovement wherein said member 1, 13 of the holder means adjacent thebattery 2 is formed with a cavity therein, the temperature sensing means10 being an element mechanically separate from the battery 2 and locatedin the cavity to contact the outside wall of the battery and to be inheat transfer relation therewith to sense battery temperature.
 2. Systemaccording to claim 1, wherein resilient means 11 are providentresiliently biassing the temperature sensor into contact with thebattery wall.
 3. System according to claim 2, wherein the temperaturesensor is located against the bottom wall of the battery.
 4. Systemaccording to claim 2, wherein the temperature sensor is located againstthe side wall of the battery.
 5. System according to claim 2, whereinthe voltage regulator and the temperature sensor form one integral unit,said unit being spring-pressed by said resilient means against thebattery.
 6. System according to claim 1, wherein the temperature sensorand voltage regulator form an integral unit located in the cavity andresiliently held therein with the temperature sensor facing the batterywhen the battery is located in position with respect to the holdermeans.
 7. System according to claim 6, wherein the member is plate-likeAnd formed with a closed cavity, the temperature sensor-voltageregulator unit and the resilient means being located in said cavity; andthermal insulation means are located at least in part in said cavity toinsulate the temperature sensor from outside temperature disturbances.8. System according to claim 1, further comprising thermal insulatingmeans insulating the temperature sensor against outside temperaturedisturbances and surrounding the temperature sensor at least in part.